An improved Dynamic material Characterisation of carbon/epoxy composites at intermediate strain rates

Abstract

This paper reports an experimental investigation on strain rate dependence of carbon/epoxy composites at intermediate strain rates. Dynamic tensile tests at strain rates between 0.1 and 200 per second are performed using a high-speed servo-hydraulic test machine equipped with an improved load introduction device. The data reduction analysis is performed to handle the inertial effect (i.e., system ringing on force measurement) during the testing. Load introduction technique is improved to mitigate the system ringing and lightweight grip systems are designed in order to increase the natural frequency of the test system. In addition, the inertial induced problems are resolved for strain measurement using Digital Image Correlation (DIC) technique. A general and robust experimental technique to characterise strain rate behaviour of carbon/epoxy composite materials are thoroughly investigated. As a result, an improved test protocol to perform dynamic mechanical testing at intermediate strain rates using a high-speed servo-hydraulic machine is proposed.